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Re: [Public WebGL] readPixles() can't access float values (OES_texture_float interaction)



On Mon, Sep 19, 2011 at 8:14 PM, Chris Marrin <cmarrin@apple.com> wrote:
Are you saying an author should discover whether or not it's possible to create a FP FBO by trying and if the FBO is incomplete after the attempt, that's an indication that it's not supported? I don't think that has precedence. Seems like it's much better to use the extension mechanism. If the attempt to enable the extension fails, then it's not a feature that can be used.
Yes it's a bit messy. But the http://www.opengl.org/registry/specs/ARB/texture_float.txt makes no stipulation if framebuffers have to support it or not.
Likewise http://www.opengl.org/registry/specs/ARB/framebuffer_object.txt does not make any such guarantee, however it does discuss various use cases with floating point attached buffers, including color.

In my (limited, desktop oriented) practice I have not yet seen a device which supports floating point textures and FBOs, but cannot handle attaching a floating point texture to an FBO. So regardless of the intent of webgl, OpenGL does not support the query you'd like to execute. The only way to execute your desired "can this thing support floating point attachments" is to try it out, unless the extension registry is updated with just such an extension.

If you'd like to provide the "try it out" semantic via some webgl extension, or weather you'll leave it up to the user is of no significance of me. As long as I can still attach floating point textures to an FBO in some manner.